6 Nov 2012

Calculate Single Contour-Line from DEM with QGIS / GDAL

In QGIS:

- from menu: Raster / Extraction / Contour

- define output name path/to/output.shp

- alter GDAL call for single contour line at 900 m asl:
gdal_contour -fl 900 "path/to/dem_raster.asc" "path/to/output.shp"


- for removing small poplygons or lines add area or length field (attr table / field calc or vector / geometry / add geometry)

- query by length or area to deselect unwanted iso-lines


Finally, you can export the contours as KML and check it in Google Earth:


I downloaded my DEM-rasters (Nord-Tirol, Ă–sterreich) HERE

4 comments :

  1. A very useful book is "Participatory Geospatial Development Using Python".

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  2. I have a spreadsheet with dozens of plant species and thousands of points for them - across N. America. I'd like to produce polygons that outline their distributions such that disjunctions are shown (so some species may have a single polygon while others will have more than one). Any ideas about how to do this quickly and efficiently?

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    1. Please consult an appropiate Q&A site like http://gis.stackexchange.com/

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